Self-repairing metal observed for the first time, pointing to the possibility that machines can fix themselves

July 19 () –

Researchers from Sandia National Laboratories and Texas A&M University, in the United States, have announced that they have achieved observe for the first time a self-healing metal. If harnessed, the newly discovered phenomenon could one day give rise to engines, bridges and planes to reverse the damage caused by wear and tearmaking them safer and more durable, as published in the journal ‘Nature’.

For the first time, Scientists have watched bits of metal crack and then snap back together without human intervention., turning fundamental scientific theories upside down. “It was absolutely amazing to see it first hand. recalls Sandia materials scientist Brad Boyce. What we have confirmed is that metals have their own intrinsic and natural ability to heal themselves, at least in the case of nanoscale fatigue damage.“.

Fatigue damage is one of the ways machines wear out and eventually break down. Repeated stress or movement causes the formation of microscopic cracks. Over time, these cracks grow and spread until the entire device breaks. The crack that Boyce and his team saw disappear was one of these tiny but consistent fractures, measured in nanometers.

“From the soldering of our electronic devices to the engines of our vehicles or the bridges we cross, these structures often fail unpredictably due to cyclic loading, causing cracks and eventually fractures,” Boyce explains. When they fail, we are faced with replacement costs, lost time, and in some cases even injury or loss of life.”

Although scientists have created some self-healing materials, most notably plastics, the notion of a self-healing metal has largely been the domain of science fiction. “Cracks in metals were expected to get bigger, not smaller. Even some of the basic equations we use to describe crack growth exclude the possibility of such healing processes.”

In 2013, Michael Demkowicz — then an adjunct professor in the department of materials science and engineering at the Massachusetts Institute of Technology, now a tenured professor at Texas A&M — began to chip away at conventional materials theory. published a new theorybased on the results of computer simulations, according to which, under certain conditions, the metal should be able to weld cracks formed by wear.

The discovery that his theory was true came inadvertently at the Center for Integrated Nanotechnologies, a Department of Energy facility run jointly by Sandia and Los Alamos National Laboratories. “Of course, we weren’t looking for it,” admits Boyce.

Khalid Hattar, now an associate professor at the University of Tennessee, Knoxville, and Chris Barr, who now works for the Department of Energy’s Office of Nuclear Energy, were conducting the experiment at Sandia when the discovery was made. They only intended to assess how cracks formed and propagated through a nanoscale piece of platinum using a specialized electron microscope technique they had developed to repeatedly pull the ends of the metal 200 times per second.

Surprisingly, 40 minutes into the experiment, the damage was reversed. One end of the crack fused together as if retracing its steps, leaving no trace of the previous injury. Over time, the crack grew back in another direction. Hattar called it an “unprecedented discovery.”

Boyce, who was aware of the theory, shared his findings with Demkowicz. “I was very glad to hear it, of course.”Demkowicz says. The professor then recreated the experiment in a computer model, corroborating that the phenomenon witnessed in Sandia was the same as the one he had theorized years before.

Much remains to be known about the self-healing process, such as whether it will become a practical tool in a manufacturing environment. “How generalizable these results are will likely be the subject of extensive investigation,” Boyce said. We show that this occurs in nanocrystalline metals in a vacuum. But we don’t know if it can also be induced in conventional metals in the air.”.

Yet despite all the unknowns, the discovery remains a leap forward on the frontier of materials science. “My hope is that this finding encourages materials researchers to consider that, under the right circumstances, materials can do things we didn’t expect.Demkowicz concludes.